0:28Skip to 0 minutes and 28 secondsWe've seen the origins of temple architecture in the Republican period. But here, I think, is really my favourite Roman building behind me, the Pantheon. We see what the Roman emperors could achieve when they brought to bear on that task their huge resources of manpower, of money, and of resources, materials from the four corners of the Roman Empire. Now religious architecture is by its nature quite conservative. Things are kept the same from generation to generation. So as we look at this building, we'll see things that are very familiar from earlier temple design. The columns, the porch, the frontal emphasis of the building, all of this looks quite traditional, quite typical.

1:03Skip to 1 minute and 3 secondsBut when we think about the size, the scale, and the materials used here, we see there's something new, radical, and bold is being done. The columns are made of single blocks of Egyptian granite. That's hugely dense, heavy, hard to carve rock that's been taken out of the quarry in Egypt in single blocks, shipped up the Nile, across the ocean, over to Italy, up the Tiber, and erected here in Rome to build this temple. So huge expense on materials. There's white, Pentelic marble in the porch. There's gleaming bronze work in the doors, and somewhere up in the roof structure. And when we go inside the temple we see a controlled riot of colours, yellows, pinks, greys, and whites.

1:38Skip to 1 minute and 38 secondsBeautiful harmony of colours really enriching and decorating this building. But the real trick at play is when you walk from this very conventional columnar porch facade, through the great bronze doors, and into the interior of the building, because then what you see is this not a conventional temple at all. It's not even a rectangular building. What you enter is a huge round space, a cylinder made of brick and concrete, and that cylinder supports a great half dome as tall again as the cylinder is wide. It's 150 ft diameter, and until the mid-20th century, in fact, that was the largest unsupported concrete dome anywhere on the planet, and it's still standing today.

2:13Skip to 2 minutes and 13 secondsAnd what this great vaulted space gives us is a sense of the heavens come down to earth. It's lit through a great space at the top, the oculus, through which a sun beam falls, lighting up an interior that is full of coloured marbles as we've seen. So you get this huge transitional effect from the conventional outside to the radical inside. A vaulted space that’s drawn from the world of Roman bathhouse architecture, vaulted geometric concrete architecture. Quite different to the world of traditional temple architecture. Now rich and amazing as this building is, in fact, we don't know whose worship it was dedicated to, which gods were honored there. We do have some clues.

3:17Skip to 3 minutes and 17 secondsThe Greek name it has, ‘Pantheon’ means ‘all the gods’. So perhaps that sense of heaven come down to earth indicates that it's for the worship of all of the divine. And in the niches around the inside of the building, people picture various Roman gods. And we know too that it had some connection to the world of emperor cult, worshipping the living or recently dead and deified emperors. In fact, this is the third Pantheon building on the site, and the first was built by the son-in-law and heir of the first Roman emperor, Augustus. That man was called Agrippa, and we still see his name on the front of the building today.

3:47Skip to 3 minutes and 47 secondsNow Agrippa, we know, offered to place a statue of Augustus inside the building, and Augustus in a great, I'm sure choreographed, show of modesty said, oh, no, no. I can't do that. I'm not a god. Not yet. So why didn't you put the statue outside the building? So there's that connection with a deified emperor. And then the building burned down in a fire in AD 80. It was rebuilt and burned down again in AD 110. And the emperor Hadrian, himself an amateur architect of some distinction, rebuilt the structure that we still see standing behind me today.

4:14Skip to 4 minutes and 14 secondsIt's a huge and impressive building, and it's been continually therefore a site of worship for nearly 2000 years, because in fact it's still a religious building today. It's the Church of St. Mary of the Martyrs. It was converted to a church when the Roman Empire went Christian. Its conversion happened in AD 608. And it's that conversion that we have to thank for its incredible state of preservation today. That and the fact that the Roman builders built it right to survive two millennia of earthquakes.

4:46Skip to 4 minutes and 46 secondsAs Rome was ruled by emperor after emperor, it acquired a new crowd of gods. Because some of the emperors, at least the good ones or the ones that posterity regarded with favour, were deified, at their death sent up into heaven to take their place among the gods. And that meant they needed temples to be worshipped in. Here in Rome and elsewhere around the Roman empire, the cult of the deified emperor, and sometimes even of the living emperor-god, became important business. And this temple just north of the Pantheon shows us how grand these temples could be.

5:16Skip to 5 minutes and 16 secondsHere these 11 columns and beautiful banded Proconnesian marble built into the side of what's now a financial building, are probably the remains of the temple of the deified emperor Hadrian, the emperor who built Hadrian's Wall in the north of Britain. Nowadays the modern street is level with the base of these columns, but if we look down, we can see that originally this temple, like so many, stood on a high podium. Over the centuries detritus washed in from the Tiber River nearby and the demolition and rebuilding of successive generations of mediaeval and modern buildings have lifted the ground level up by five or six metres.

5:49Skip to 5 minutes and 49 secondsBut originally worshippers arriving to pay homage to the deified emperor-god Hadrian here would have seen this temple towering above them. Roman emperors mediated between the Roman gods and the people. In fact, they all held the office of pontifex maximus or chief priest. So it's not surprising that religious iconography including temple buildings were pictured on some of their coins, even when the emperors themselves were not those we might think of as typically religious people. Here, for example, is Caligula. So here on the front you see the emperor’s titles running clockwise around the coin.

6:34Skip to 6 minutes and 34 secondsAnd on the bottom a caption that shows that we're looking at the personification here of the goddess piety or the figure piety, Pietas, in Latin, rather than a portrait of the emperor. The emperor whose piety is being celebrated here is a distinctly impious emperor, Caligula, one of the very worst of the Roman emperors, in fact, who was accused of incest with his sisters, and then eventually assassinated by disgruntled members of his military staff. It's the back of this coin that really interest us here. This is a temple to his great-grandfather the deified emperor Augustus. Now we know that this temple was there in Rome, but we don't know exactly where.

7:08Skip to 7 minutes and 8 secondsA lot of authors talk about it, but it's totally lost in the archaeological record. So this coin portrait that shows a scene of sacrifice outside that temple is really precious evidence. If we look at the coin, we can see garlands strewn between the columns of the temple. We can see statues in the triangular pediment, and statues standing on the roof. It gives us a lovely crisp idea of how that temple may have appeared, and how important it was for Caligula to show religious piety and duty towards his deified great-grandfather Augustus, no longer the emperor, but Augustus the god. Later emperors carried on this role of chief priest and mediator with the gods.

7:43Skip to 7 minutes and 43 secondsHere, for example, is Nero, also not a character we think of as terribly religious in the conventional sense. But he boasted that he had managed to shut the gates of the Temple of Janus. And if you turn over the coin, there is the temple of Janus. A temple with a slightly unusual design that incorporated a pair of great gates, and the deal was that these gates would be shut ceremonially whenever there was peace throughout the entire Roman empire both by land and sea. So closing them signified no wars going on anywhere. It was actually quite a rare achievement for an emperor. So for Nero to shut these gates was important, and he advertised the fact on his coins.

8:35Skip to 8 minutes and 35 secondsThe Pantheon is a really stupendous piece of architecture. As I say, I think it's my favourite building in all of Rome. And whoever the builder behind it was, whether it's the direct influence of the architect emperor Hadrian, or perhaps Apollodorus of Damascus, his predecessor Trajan's chief architect, we can say that whoever built this was really a genius. But I think we can catch them out on a simple mistake. The column shafts behind me, those mighty 48 ft Aswan granite monoliths, should actually be about 60 ft tall. And we know this, because if you look at the outside of the building, above that triangular pedimented porch, you see the outline, the imprint of where the porch should actually have been.

9:12Skip to 9 minutes and 12 secondsIt should have been taller. Now who knows why that happened. Perhaps, when these expensive heavy column shafts turned up in Rome, they were simply the wrong size and it was too late to send them back. Perhaps the original consignment of taller columns was lost in a shipwreck. Perhaps when they arrived in Rome, the emperor decided he wanted to use them somewhere else instead. Whatever happened had effects that rippled throughout the porch of this building. Because classical architecture, like temple architecture, is based on strict mathematical rules of proportion. If you make those columns shorter, you have to make them narrower.

9:40Skip to 9 minutes and 40 secondsIf you do that, the gaps between the columns get wider, and the whole thing starts to falter and break the rules. So to a purist eye, there are some mistakes in the porch behind me. But looking at this magnificent building, I think we can safely say they got away with it.

Part VII – ‘The heavens come down to the earth’

At first glance the Pantheon shares may of the same features as the Republican temples we looked at earlier this week, such as the columns or the large porch. But it’s really only when you step inside this grand building that you get a sense of what makes this temple so special.

In this video I explain further and reveal why this temple is my favourite ancient building in Rome.

As you watch the video, you may like to think about the following:

What do you think would have come to mind when the ancient Romans first walked through those great bronze doors and were confronted by the stunning variety of coloured marble and other decorative materials inside?

Why do you think the difference between the conventional exterior and radically different interior of the Pantheon was so significant?